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Mic-ing an Amp

Discussion in 'Recording Gear and Equipment [BG]' started by Sir Edward V, Jul 31, 2007.


  1. Sir Edward V

    Sir Edward V Not Actually Knighted... Yet!

    Dec 11, 2006
    Massachusetts
    Are there any techniques to mic-ing an amp? I was messing with it today and I could tell there were differences in where I placed the mic in relation to the speaker that changed the sound. I think closer to the cone it got brighter (more highs) and as I moved to the rim it got deeper.

    I'm pretty sure different placements have different industry names and whatnot, so does someone want to clue me in?

    I did a quick look on google and on the search function here, I couldn't find anything helpful. Maybe I was searching for the wrong terms.

    I have a 1x15 combo, where would be a good place to place the mic? or a couple of good places?

    Thanks, if there are already threads on this, just direct me to them.
     
  2. also play with the distance from the cab... some of the low frequency waves only form properly a few feet away from the speaker... plus this will help get the full spectrum of your cab instead of just the one speaker you are micing (in your case it will pick up the tweeter too).
     
  3. Sir Edward V

    Sir Edward V Not Actually Knighted... Yet!

    Dec 11, 2006
    Massachusetts
    yeah I dont think I have a tweeter, but thats good to know for other cabs
     
  4. hunta

    hunta

    Dec 2, 2004
    Washington, DC
    It also depends on what kind of mic you're using. Different mics have different pickup patterns. If you're using an SM57 it's pretty much unidirectional, others can have larger diaphrams and will pick up a wider "cone" of sound. Different mics work better at different distances.

    I'm assuming you're using an SM57 or something similar. You want to place it very close to the grill of your speaker cabinet (not touching it), maybe an inch away. I usually position it pretty close to the outside of the speaker cone.

    I have generally found that there isn't much difference in the sound from a properly positioned mic and a DI box, so I just go with a DI.

    The different terms I know of for mic positioning are generally for 2 mics, not one. Like XY or AB position.
     
  5. anderbass

    anderbass

    Dec 20, 2005
    Phoenix. Az.
  6. I would mic close with a SM57 about halfway between the edge and cone and run a line direct or some sort of room mic about 5 feet out with the 57.

    It's all preference.
     
  7. A large diaphragm condenser picks up a lot of bass frequencey. Something like an MXL 1001 can be got cheap and they sound fine, another good cheap Chinese condenser is the Apex 430. I would do as above and close mic and then use a more sensitive mic for the depth, an sm57 will sound thin alone.
     
  8. joelb79

    joelb79

    Mar 22, 2006
    Lansing, Michigan
    In the studio, a large diaphragm omni-directional condenser microphone. 12" from the speaker on axis. A Neuman U87 would be perfect for a nice warm sound.

    Live, a Beyer Dynamic M88 works GREAT. Little pricey. Locate it close enough to isolate the sound, but not too close as the grill will rattle. Aim at the center of the speaker, from an angle around 45 degrees.
     
  9. Jim Roseberry

    Jim Roseberry

    May 24, 2007
    The U87 is a great choice to mic a bass cab.
    BUT... If you're going to use it in omni, it's critical that you have a decent room.

    If you mic with a condenser, make sure to use a unit that has a pad. Otherwise, the cab will likely overload the sensitive mic.

    Another good inexpensive bass cab mic is the Rode NT2.
    MD421 is a good large diaphragm dynamic mic


    Jim Roseberry
    www.studiocat.com
    jim@studiocat.com
     
  10. seamonkey

    seamonkey

    Aug 6, 2004
    Just a technique suggestion. Record yourself direct, then "re-amp" it by playing back through an amp and using a mic to record it.

    With good isolation headphones you can figure out where best to place the mic dynamically. Maybe even a couple of different places during a song.

    If you're using a PC, also checkout many of the VST plugins that simulate amps and cabinets. Many are very good. They essentially work like the "re-amp" above.
     
  11. bluestarbass

    bluestarbass

    Jul 31, 2007
    Indianapolis
    I dont wanna call anyone out here but alot of these things are a bit misinformed. Sometimes chat rooms like this can do some more harm than good so let me see if i can clarify this statement.

    Hes right about the 57, thats a cardioid pickup patter, just aim one end of the mic against the speaker cone. Sir edward you were doing the smartest thing on your own. Moving the mic around the cone will make the biggest difference in your recording chain. Bigger than your pres or your converters or anything. Mic placement is key.

    I couldnt disagree more that a DI sounds like a mic'd cab. 2 totally different tones. I use a DI as a backup and abackup only. As someone else suggested its nice if your gonna reamp. Theres no substitute for a good mic'd cab, if you have good mics and a good amp. If you have like an EA or something thats super uncolored then hunta's probably more accurate.

    As far as patterns go i dont think id ever put a stereo pair in xy on a cabinant. XY is designed to give you a good stereo field. A bass cab has no stereo field basically. Unless youve got like a wall of bass cabs, or like 2 8x10s spaced 10 feet apart this will do you no good. AB is a new one on me. Unless you mean just 2 mics wherever you feel like putting them, ive never heard of that term.

    My preference on a bass cab, i usually use 4 tracks. One i put a d112 on the lower cone really really close to the speaker. In fact i take off the grill so i can get close enough. 2, usually a 421 up on the middle cone with abit of bass rolloff to catch more of the click and mids. 3, the condensor in omni is a good suggestion but what Jim said is an even better suggestion. Omni does pick up bass frequencies better but itll sound aweful if your recording somewhere that isnt treated. Stick to cardioid if its an untreated room. And last a DI track in case I hate the tone I can go back and reamp it later.
     
  12. joelb79

    joelb79

    Mar 22, 2006
    Lansing, Michigan
    The D112 is tailored for Kick Drum not bass guitar. The frequency response curve adds in a lot of low end, which is not necessarily a good thing for bass guitar.

    [​IMG]

    I've noticed that most sound engineers who use the D112 live tend to pull out the low frequency on the channel which tends to make for a rather crappy sounding bass guitar.

    Hence my suggestion to use a Beyer M88. The frequency curve is nearly flat from 30hz-20,000Hz with a slight rise starting at around 1khz. It is also cardioid. Its also the standard for horn micing.

    http://northern-america.beyerdynamic.com/cms/download.php?filename=m88_data_en.pdf
     
  13. WayneP

    WayneP Supporting Member

    Oct 11, 2004
    Corpus Christi, Texas
    [font=comic sans ms,verdana,arial]
    Noo-o-o-o-o!!! The 57 is not a bass microphone! It rolls out at –5 dB/octave or more below 200 Hz!


    [​IMG]

    Yup – a broad 100 Hz boost like that is going to muddy things up considerably. Still, the response chart helps you see what needs to be done. A 1-octave parametric filter cut 10 dB would flatten it out nicely.

    Regards,
    Wayne A. Pflughaupt
    [/font]
     
  14. joelb79

    joelb79

    Mar 22, 2006
    Lansing, Michigan
    I didn't think they roll off that bad! I've never seen that ugly a response curve on an SM57. Shure advertises something different.

    I should add do NOT record your bass without a DI line, ESPECIALLY when using an SM57.
     
  15. WayneP

    WayneP Supporting Member

    Oct 11, 2004
    Corpus Christi, Texas
    [font=comic sans ms,verdana,arial]
    Really? Wow. I got that straight off their website!

    Regards,
    Wayne A. Pflughaupt
    [/font]
     

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